This invention relates to a sealing arrangement of the type used for sealing off two machine elements that undergo axially reciprocal motion with respect to one another. A rod or piston seal is arranged in a groove of the second machine element. The groove is open in the direction of the first machine element, and houses a seal ring and a prestress ring made of elastomeric material. The seal ring has an essentially T-shaped cross-section and touches the surface of the first machine element that is to be sealed with the sealing surface of a radial ridge, forming a seal. The prestress ring is arranged between the base of the groove and the axial ridge of the seal ring under elastic prestress.
Such a sealing arrangement is described in German Patent No. 41 40 833 C3, FIG. 2. (The contents of corresponding U.S. Pat. No. 5,433,452 are incorporated herein by reference for their teachings of the state of the art.) In the unpressurized state, the low-pressure-side groove flank forms an acute angle with the face of the axial ridge which lies directly opposite to it, this angle being open toward the surface to be sealed. When pressure is applied and/or due to the friction between the seal ring and the surface to be sealed, the seal ring can be pivoted toward the low-pressure side in such a way that it forms a sealing edge relative to the surface to be sealed, with the seal ring delimiting a wedge gap with the surface to be sealed, which gap opens toward the low-pressure side. The transition regions from the faces of the radial ridge to the sealing surface and to the axial ridge are formed with sharp edges in each instance, where the sharp-edged transition region of the faces to the sealing surface result in a relatively high rate of abrasive wear, due to the relative back and forth mobility of the surface to be sealed relative to the seal ring. Consequently, the sealing edge can be damaged during use. In the transition region from the faces of the radial ridge to the axial ridge, high notch stresses prevail during use of the sealing arrangement, and these can lead to tearing of the ring in this region.